Oil Smell from ventilation system in 2009 E350
I have a burnt oil smell coming from the vents in my heat/cooling vents in a 2009 Mercedes E350. I have had the engine cleaned and almost no signs of any oil leak. Near the oil filter these seems to be just a slight film/dirt on the engine and a slight smell when the engine is running. The rest of the engine seems clean and surprisingly has no smell except near the oil filter assembly. I recently had the oil filter assembly replaced so it should have all new o-rings there. The few drops of oil not a concern but the smell gettin into the passenger compartment is. There is no smell when the ventilation system is off.
PS: I have checked the covers on the back of the engine and replace the one that had a few drops of oil below it.
Yes, do as Scotty (and every competent mechanic) will do: Put in the dye, get the yellow goggles and the blacklight. Go for a drive on the highway, and then, after the engine cools a bit, follow the dye trail. As Scotty sometimes says about what his father told him, don't assume that you have but one leak. You may find several.
try changing the PCV valve